It is known that organic materials are damaged by light, radiation, heat or oxygen. There are already numerous documents which describe compounds for stabilizing organic material against the effects of light and heat. Some of these documents relate to compounds based on 2,2,6,6-tetraalkylpiperidine. These stabilizers must be present in sufficient concentration especially at the exposed areas of the organic material in order to provide effective protection. The low molecular mass representatives from the class of substance of the 2,2,6,6-tetraalkylpiperidines have the advantage of migrating rapidly to the areas particularly exposed to the damaging influences, where they exert their protective influence. Nevertheless, they have the disadvantage that they possess excessive volatility and, in addition, are readily extractable from the organic material. The higher molecular mass representatives of this class of substance, although not so readily extractable, are much slower to migrate. In the art this problem is often solved by employing a mixture of low molecular mass (rapidly migrating) and high molecular mass (slowly migrating) stabilizers.
A considerable number of stabilizer mixtures based on sterically hindered amines have been presented which possess the abovementioned disadvantages to a lesser degree if at all. By way of example there may be mentioned mixtures as described, for example, in U.S. Pat. No. 4,692,486, U.S. Pat. No. 4,863,981, U.S. Pat. No. 4,957,953, WO-A-92/12201, WO-A-94/22946, EP-A449685, EP-A-623 092, GB-A-2 267 499, DE-A-1 9613 982 and in Research Disclosure No. 34549 (Jan. 1993). However, there is a constant demand for new, more effective stabilizer mixtures which give organic material improved photoprotective or service properties.
It has surprisingly now been found that the compound I in a mixture with the compound II and, if desired, with the compound III stabilizes organic material extremely well against the damaging effects of light, radiation, heat or oxygen.